The health consequences of smoking are directly related to smoke exposure. Although toxicologically and pharmacologically relevant exposure to nicotine, carbon monoxide (CO) and other components of tobacco smoke occurs at lower bronchial and lung alveolar tissue, quantitative measures of smoke exposure are ordinarily indexed by puffing parameters - measures of mouth exposure. Mouth-level exposure is only weakly and variably correlated with systemic smoke exposure suggesting that inhalation measures may be better quantitative predictors of exposure. This proposal will compare puff topography parameters and inhalation parameters to determine which method better models human smoke exposure. Puff topography measures will be collected using the lab-based CReSS system, and inhalation measures will be collected concomitantly using a recently-developed respiratory monitoring system based on inductive plethysmography (LifeShirt). Changes in plasma nicotine and exhaled CO (boosts) will be used as biomarkers of exposure to tobacco smoke. The specific research aims of the study are (1) to determine if a set of inhalation parameters is better at predicting nicotine and CO boosts compared to a set of puff parameters; (2) to determine changes in puff and inhalation parameters induced by tobacco abstinence and smoking an "ultra-light" highly ventilated cigarette (manipulations known to change puff parameters); and (3) to determine if changes in puff and inhalation parameters predict biomarkers of exposure (nicotine and CO boosts) in conditions of tobacco abstinence and when smoking a highly ventilated ("low-yield'). These aims will be addressed in a laboratory-based within subject cross-over study. Approximately 135 male and female established smokers, age 18 or over, who usually smoke a full flavored (tar = 16 mg) filtered cigarette will be recruited. Smoking status will be verified biochemically and by self-report. Subjects will participate in three counter-balanced laboratory sessions. In each session they will smoke a single cigarette through a puff topography mouthpiece while wearing the LifeShirt. In one session, they will smoke their own brand of cigarette; in another they will smoke their own brand after overnight abstinence; and in another session they will smoke an "ultra-light cigarette" (tar = 5 mg) that will be flavored similarly to their own brand (menthol or non menthol). The proposed research will serve as an initial step to evaluate the practical application of a new inductive plethysmography technology to model human smoke exposure. As such, this proposal represents a unique exploration of an additional dimension in measuring smoke exposure. This method has the potential to fundamentally change the measurement of smoke exposure from the mouth to the lungs, the site of relevant pharamcodynamic activity and manifestation of many pathological consequences. Although there is strong epidemiological data that links cigarette smoking to addiction and pathology, there is relatively little data that links exposure in an individual to the behavior of smoking or its pathological consequences (e.g. addiction, lung disease). Previous measures of exposure have relied upon puffing behavior which describes the entry of smoke into the mouth, however exposure relevant to pathology occurs in the lung. The present proposal is the first to parametrically compare puffing and inhalation methods in an effort develop better and more relevant methods to quantify smoke exposure. [unreadable] [unreadable] [unreadable]